Amateur Radio August 2008
Delivery expected from 5 August
The first weekend in July saw over 100 people at Monash University Gippsland Campus in Churchill for the 11th annual GippsTech technical conference. Yes – I must declare a conflict of interest, I am the Chair of the Organising Committee.
The program overflowed with technical content, primarily related to matters VHF, UHF and above. Novice and experienced speakers presented a wealth of material at a level that almost everyone could follow – even if sometimes only in principle, and not the details. While the amateurs enjoyed the technical content at Churchill, Gordon VK3PAA and Pauline Corrigan led the partners on a tour of regional highlights over the day and half of the conference. They visited three wineries during Saturday, with lunch at the Tinamba Hotel – well known in the region for the quality of its meals.
The technical program ran from 0945 to 1800 on Saturday and 0900 to 1300 Sunday. The tea/coffee breaks were shorter in duration than we usually plan, due to the number of topics on offer, and the lunch breaks allowed for good food provided by the local Lions Club, lots of discussion and some low key trading of a variety of goodies.
On behalf of the Eastern Zone Amateur Radio Club (Inc.), thanks to all who contributed: the club members and attendees who contributed in so many ways at the event and during the planning phase; the speakers, those who brought give away items, the Churchill Lions Club, Monash University Gippsland Campus and those that provided items for the raffle. Special thanks must go to Bryan and Richard, and their bosses, for the significant number of 24 GHz parabolic dish antennas, some included radomes, others were just the parabolic reflector. These high quality dishes sold rapidly at bargain prices. Even better for the local club, the proceeds were donated to the organising committee.
Many attendees enjoyed a get together on the Friday evening at a local bistro and almost 100 attended the conference dinner on the Saturday evening. During the breaks in the program and the meals, there was a large amount of discussion stimulated by the presentations during the weekend.
On Sunday afternoon, most started the often long trip home – we had attendees from VK1, VK2, VK3, VK4, VK5, VK6, VK7 and ZL.
Apart from following though on those thoughts stimulated by the weekend’s presentations and informal discussions, there just remains the task of leveraging the documents from the presenters for the Proceedings volume – which should be available just in time for next year’s event on the weekend of July 11 and 12.
August – a VK activity month
Traditionally, the August issue of AR has had some focus on the Remembrance Day Contest. We fitted a loose link to that focus onto the cover, with the MCR-1 ‘Biscuit Tin’ radio, with a brief story about this radio on page 31. The contest rules are printed on pages 44 and 45.
This year the RD Contest coincides with the International Lighthouse and Lightship Weekend (ILLW) – not a contest but an international activity weekend. For further details, look at the official ILLW website at http://illw.org/ Whilst most of the ILLW participants may not be focussing on the RD Contest (very understandable), I am sure that you will be able to request a report and number from them if you ask nicely.
The final weekend of August sees the running of the ALARA Contest. Open to all, this contest represents a great chance for the “paper chasers” – those looking to qualify for awards. There should be many YL operators active over the weekend, so you should have a good chance to find the contacts needed for the ALARA Award – VK & ZL amateurs need only 10 contacts with ALARA YLs in four Australian call areas to qualify.
The days are slowly getting longer. Here in the southern sates, the weather brings cold mornings, but occasional cool but sunny days. As the weather improves and the days grow longer, may you all make the time to progress the long list of outside amateur radio projects that have been accumulating over the wet winter months.
73, Peter VK3KAI
Quite a contrast in technologies: this month’s cover shows the World War II vintage MCR-1 ‘Biscuit Tin’ radio and the modern IC-7700 solid state transceiver.
You can read a brief outline of the MCR-1 on page 31 of this issue, with the detailed IC-7700 review commencing on page 27.
Photo of the MCR-1 by Jim Gordon VK3ZKK. Photo of the IC-7700 courtesy of Icom.
Table Of Contents
The Two Letter Call Sign Ballot Michael Owen VK3KI
Don’t panic! The sun is spot-on Dr. Tony Phillips Science@NASA
DXing from the Mighty Mo Bruce R Kendall VK3WL/9V1WL
The Spy in a Biscuit Tin: Miniature Communications Radio MCR-1 John Nieman
A 5 W CW transmitter for 1.8, 3.5 and 7 MHz with QSK Drew Diamond VK3XU
Further reflections on a wideband return loss bridge Paul McMahon VK3DIP
An essential piece of equipment every home-brewer must have: an RF probe Grant McDuling VK4JAZ
Icom IC-7700 HF – 6 m all mode transceiver Bill Roper VK3BR
DXing from the Mighty Mo
Bruce R Kendall VK3WL
The author gives readers both an understanding of the thrill experienced in operating from the amateur radio station KH6BB located on board the USS Missouri (Mighty Mo), the last of the great battleships built for the US Navy, located in Pearl Harbour, and the sense of history felt whilst on board the mighty battleship. One is reminded that Mighty Mo hosted the unconditional surrender of Japan to US and Allied military personnel whilst anchored in Tokyo Bay at the conclusion of World War II.
He also gives us an overview of the mighty battleship itself and, in particular, the tremendous hospitality he experienced throughout the time he was on board.
Also, we are given brief but helpful advice on how to operate whilst on the Hawaiian Islands, in general, as well as more general advice to ensure your visit is both enjoyable, and cost effective.
The Two Letter Call Sign Ballot
Michael Owen VK3KI
WIA president Michael Owen VK3KI spells out the requirements and processes to be followed for the forthcoming ballot for available two letter callsigns. Details are also available on the WIA website.
A 5 W transmitter for 1.8, 3.5 and 7 MHz with QSK
Drew Diamond VK3XU
‘Offered here are plans for a "sweet" little CW transmitter for three popular bands. It is an improved model, based largely upon a previous pattern published in the QRP journal Lo-Key (Reference 1).
Output power is adjustable between 0 and 5 W into 50 ohms from a 13 V dc supply. Frequency range is from 1.75 (1.8 MHz) to about 1.875 MHz, 3.5 to 3.75 MHz, and 7.0 to 7.5 MHz. Harmonics are measured at greater than 50 dB below fundamental.
The sturdy class-B power amplifier (Reference 2) can withstand extreme load mismatch (including accidental short or open-circuit load) for reasonable periods without damage, and remains stable, even when feeding less than perfect loads. In operation, solid-state break-in, or "QSK" T/R, allows the user to listen on the frequency in the spaces between words and some characters, as they are sent’.
So begins another offering from author Drew Diamond VK3XU, in how he chose to design and build a 5 watt transmitter for the 1.8, 3.5 and 7 MHz amateur bands. Drew then leads the reader through both the construction techniques used, supporting those decisions with the practical, functional reasons why this methodology was employed.
An article for the home builder that, one knows from past experience, will work and work well, upon completion.
Further reflections on a wideband return loss bridge
Paul McMahon VK3DIP
Author Paul McMahon VK3DIP wrote this article is response to correspondence received after publication in AR of his previous article (A simple wideband return loss bridge revisited, AR, June, 2007, Page 20) – correspondence in the form of ‘questions, comments, and the results of tests on their versions of the RLB’.
This article attempts to summarise this correspondence plus inject detail of additional work he has done on developing his RLB from the original offering.
The article essentially covers responses to such questions as ‘how does it work’, why this or that option was used, and would variations on certain theoretical or building themes be equally successful.
Paul then explains, in significant detail, how he developed his latest RLB, and the reasons why he choose to do things the way he did, all the while noting that other measures may give similar or close comparative results.
To those interested in this aspect of amateur radio, and who are keen builders, this article will be of considerable interest.
Updated Figure 1 corrects an error - available below for download.
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Page Last Updated: Friday 31 October 2008 at 13:22 hours